Inactivation kinetics of Bacillus cereus vegetative cells and spores from different sources by antimicrobial photodynamic treatment (aPDT). (May 2021)

• Record Type: Journal Article
• Authors: Prado-Silva, Leonardo do; Alvarenga, Verônica O.; Braga, Gilberto Ú.L.; Sant'Ana, Anderson S.
• Is Part Of: Lebensmittel-Wissenschaft + Technologie =. Volume 142(2021)
• Publication Date: 2021-05
• Subjects: Emerging technology -- Nonthermal treatment -- Pathogen -- Spoilage -- Phenothiazine dye; Food industry and trade -- Periodicals; Food -- Composition -- Periodicals; Microbiology -- Periodicals; Nutrition -- Periodicals; 664.005
• DOI: 10.1016/j.lwt.2021.111037
• Languages: English
• ISSNs: 0023-6438

Abstract

Abstract: Antimicrobial photodynamic treatment (aPDT) is a promising alternative to conventional thermal inactivation methods. This study aimed to evaluate Bacillus cereus vegetative cells' inactivation and spores by aPDT with new methylene blue (NMB) as photosensitizer (PS) using red light. The efficacy of aPDT was determined initially by minimal inhibitory concentration (MIC) of NMB at different concentrations and fluences. Cluster analysis from the results of MIC grouped B. cereus strains according to their aPDT susceptibility. Then, four strains (B63, B3, 436, and ATCC 14579) were selected for a survival study of aPDT with NMB in three concentrations (5, 50, and 100 μM). The viability of B. cereus vegetative cells and spores was reduced in all tested fluences. The strain ATCC 14579 (vegetative cells and spores) was the most susceptible to aPDT at relatively low fluence (25 J/cm 2 ). The Weibull model presented a good fit for the inactivation data estimating the kinetic parameters δ (first decimal reduction) and p (shape parameter). This study contributes to the knowledge of the behavior of different strains of B. cereus regarding an emerging method of microbial inactivation. The variability of inactivation among strains will allow the development of more reliable processes. Highlights: Antimicrobial photodynamic treatment (aPDT) for inactivation of B. cereus is effective. Cluster analysis grouped strains according to aPDT susceptibility. Variability among the strains of the same origin was observed. The Weibull model was able to estimate the inactivation kinetic parameters of aPDT.